1 files changed, 22 insertions, 18 deletions

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index ffa7cc3370c7..4c3ce7a0a7a4 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -1244,7 +1244,7 @@ static int set_range_writeback(struct extent_io_tree *tree, u64 start, u64 end)
 
         while (index <= end_index) {
                 page = find_get_page(tree->mapping, index);
-                BUG_ON(!page);
+                BUG_ON(!page); /* Pages should be in the extent_io_tree */
                 set_page_writeback(page);
                 page_cache_release(page);
                 index++;
@@ -1523,7 +1523,7 @@ again:
                         goto out_failed;
                 }
         }
-        BUG_ON(ret);
+        BUG_ON(ret); /* Only valid values are 0 and -EAGAIN */
 
         /* step three, lock the state bits for the whole range */
         lock_extent_bits(tree, delalloc_start, delalloc_end, 0, &cached_state);
@@ -2200,7 +2200,6 @@ int end_extent_writepage(struct page *page, int err, u64 start, u64 end)
                 /* Writeback already completed */
                 if (ret == 0)
                         return 1;
-                BUG_ON(ret < 0);
         }
 
         if (!uptodate) {
@@ -2353,7 +2352,6 @@ error_handled:
                                 if (ret == 0)
                                         goto error_handled;
                         }
-                        BUG_ON(ret < 0);
                 }
 
                 if (uptodate) {
@@ -2405,6 +2403,10 @@ btrfs_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs,
         return bio;
 }
 
+/*
+ * Since writes are async, they will only return -ENOMEM.
+ * Reads can return the full range of I/O error conditions.
+ */
 static int __must_check submit_one_bio(int rw, struct bio *bio,
                                        int mirror_num, unsigned long bio_flags)
 {
@@ -2477,7 +2479,8 @@ static int submit_extent_page(int rw, struct extent_io_tree *tree,
                     bio_add_page(bio, page, page_size, offset) < page_size) {
                         ret = submit_one_bio(rw, bio, mirror_num,
                                              prev_bio_flags);
-                        BUG_ON(ret < 0);
+                        if (ret < 0)
+                                return ret;
                         bio = NULL;
                 } else {
                         return 0;
@@ -2498,10 +2501,8 @@ static int submit_extent_page(int rw, struct extent_io_tree *tree,
 
         if (bio_ret)
                 *bio_ret = bio;
-        else {
+        else
                 ret = submit_one_bio(rw, bio, mirror_num, bio_flags);
-                BUG_ON(ret < 0);
-        }
 
         return ret;
 }
@@ -2525,6 +2526,7 @@ static void set_page_extent_head(struct page *page, unsigned long len)
  * basic readpage implementation.  Locked extent state structs are inserted
  * into the tree that are removed when the IO is done (by the end_io
  * handlers)
+ * XXX JDM: This needs looking at to ensure proper page locking
  */
 static int __extent_read_full_page(struct extent_io_tree *tree,
                                    struct page *page,
@@ -2687,6 +2689,7 @@ static int __extent_read_full_page(struct extent_io_tree *tree,
                                          end_bio_extent_readpage, mirror_num,
                                          *bio_flags,
                                          this_bio_flag);
+                        BUG_ON(ret == -ENOMEM);
                         nr++;
                         *bio_flags = this_bio_flag;
                 }
@@ -2713,10 +2716,8 @@ int extent_read_full_page(struct extent_io_tree *tree, struct page *page,
 
         ret = __extent_read_full_page(tree, page, get_extent, &bio, mirror_num,
                                       &bio_flags);
-        if (bio) {
+        if (bio)
                 ret = submit_one_bio(READ, bio, mirror_num, bio_flags);
-                BUG_ON(ret < 0);
-        }
         return ret;
 }
 
@@ -2830,7 +2831,11 @@ static int __extent_writepage(struct page *page, struct writeback_control *wbc,
                                                        delalloc_end,
                                                        &page_started,
                                                        &nr_written);
-                        BUG_ON(ret);
+                        /* File system has been set read-only */
+                        if (ret) {
+                                SetPageError(page);
+                                goto done;
+                        }
                         /*
                          * delalloc_end is already one less than the total
                          * length, so we don't subtract one from
@@ -3141,7 +3146,7 @@ static void flush_epd_write_bio(struct extent_page_data *epd)
                         rw = WRITE_SYNC;
 
                 ret = submit_one_bio(rw, epd->bio, 0, 0);
-                BUG_ON(ret < 0);
+                BUG_ON(ret < 0); /* -ENOMEM */
                 epd->bio = NULL;
         }
 }
@@ -3257,10 +3262,8 @@ int extent_readpages(struct extent_io_tree *tree,
                 page_cache_release(page);
         }
         BUG_ON(!list_empty(pages));
-        if (bio) {
-                int ret = submit_one_bio(READ, bio, 0, bio_flags);
-                BUG_ON(ret < 0);
-        }
+        if (bio)
+                return submit_one_bio(READ, bio, 0, bio_flags);
         return 0;
 }
 
@@ -4090,7 +4093,8 @@ int read_extent_buffer_pages(struct extent_io_tree *tree,
 
         if (bio) {
                 err = submit_one_bio(READ, bio, mirror_num, bio_flags);
-                BUG_ON(err < 0);
+                if (err)
+                        return err;
         }
 
         if (ret || wait != WAIT_COMPLETE)